Encapsulating structure of flexible OLED device and flexible display device

ABSTRACT

An encapsulating structure for encapsulating a flexible OLED device includes a flexible substrate, a first flexible thin film encapsulating layer, a TFT array, an OLED device, a second flexible thin film encapsulating layer, an adhesion layer, a third flexible thin film encapsulating layer, and a polarizer layered in order. One or more barrier layers are arranged on the TFT array disposed on lateral sides of the OLED device, and the second flexible thin film encapsulating layer covers the OLED device and the one or more barrier layers. The present invention also proposes a display device having the encapsulating structure.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of display technology, andmore particularly, to an encapsulating structure for encapsulating aflexible organic light-emitting diode (OLED) device and a flexibledisplay device with the encapsulating structure.

2. Description of the Prior Art

Organic light-emitting diode (OLED) devices have a feature ofself-emission. A very thin organic coating layer and a glass substrateare adopted by the OLED devices. When electric current flows, organicmaterial emits light. In contrast to the conventional liquid crystalpanels, active matrix organic light emitting diode (AMOLED) panels havefeatures of rapid response, high contrast, wide viewing angle, etc. Inaddition, the AMOLED panels have a feature of self-emission withoutusing backlight modules. Compared with the conventional liquid crystalpanels, the AMOLED panels are thinner and lighter. Also, costs arereduced because backlight modules are not used in the AMOLED panels.Owing to the features and advantages, the AMOLED panels are of goodprospect.

OLED devices have more advantages and have good prospects. But, thereactive metal formed the metallic cathode in OLED devices is highlysensitive to water vapor and oxygen in the air. The reactive metal isinclined to react with the seeped water vapor and oxygen, which easilyaffects the injection of electric charge. Besides, the seeped watervapor and oxygen tends to react with organic material chemically. Suchreactions are the main causes of poor performance of OLED devices andshort lifespan of OLED devices. Thus, the encapsulating technique isvery important for OLED devices. Currently, there are many methods forencapsulating OLED devices such as the glass encapsulating method, thefrit encapsulating method, and the thin film encapsulation (TFE) method.The most ordinary method of the TFE method is to encapsulate OLEDdevices with transparent thin films. The encapsulation method hasadvantages of operating simply and keeping the encapsulated items lightand thin.

Moreover, an outstanding feature of the OLED devices is to displayflexibly. One important development for the OLED devices is adoption ofbendable, lightweight, and portable flexible display devices fabricatedfrom flexible substrates. Flexible OLED devices have been thrown to themarket. Flexible thin film encapsulating is adopted by flexible OLEDdevices, which means whether flexible thin film encapsulating caneffectively blocking off water vapor and oxygen or not is a key factorof lifespan of the devices. If flexible material is substituted forglass substrates and encapsulating covers having an excellent quality ofblocking off water vapor and oxygen, then the problem of blocking offwater vapor and oxygen has to be resolved. FIG. 1 shows an encapsulatingstructure of a conventional flexible OLED device. As FIG. 1 shows, theencapsulating structure comprises a rigid substrate 1 (can be removedafter the whole encapsulating structure is completed), a flexiblesubstrate 2, a first flexible thin film encapsulating layer 3, athin-film transistor (TFT) array 4, an OLED device 5, a second flexiblethin film encapsulating layer 6, an adhesion layer 7, a third flexiblethin film encapsulating layer 8, and a polarizer 9 layered in order. Thesecond flexible thin film encapsulating layer 6 covers the top side andthe lateral sides of the OLED device 5. The rigid substrate 1 can befabricated as a grid substrate for fulfilling the requirement offlexibility of the whole encapsulating structure. The flexible substrate2 can be fabricated by material such as polyimide (PI) or polyethyleneterephthalate (PET). The first flexible thin film encapsulating layer 3,the second flexible thin film encapsulating layer 6, and the thirdflexible thin film encapsulating layer 8 are formed by inorganic barrierlayers and organic buffer layers layered alternatively.

In addition to the flexible thin film encapsulating layers arranged onthe bottom side and top side of the above-mentioned OLED devices, theOLED devices further comprise more structural layers for blocking offwater vapor and oxygen, which completely fulfills the demands of thelifespan of the OLED device. But, the lateral sides of the OLED devicesonly comprise a flexible thin film encapsulating layer and an adhesionlayer for blocking off water vapor and oxygen. The adhesion layer ispoorer for blocking off water vapor and oxygen. Because the material forthe flexible thin film encapsulating layer is restricted, only theflexible thin film encapsulating layers can be arranged on the lateralsides of the OLED devices for blocking off water vapor and oxygen, whichcannot fulfill the demands of the lifespan of the OLED device.

SUMMARY OF THE INVENTION

In view of this, an object of the present invention is to propose anencapsulating structure of a flexible OLED device. The presentencapsulating structure is effective for improving the encapsulatingstructure of the lateral sides of the flexible OLED device. The featureof the present encapsulating structure is to block off water vapor andoxygen so that the lifespan of the OLED device can be prolonged.

According to the present invention, an encapsulating structure forencapsulating a flexible organic light-emitting diode (OLED) devicecomprises a flexible substrate, a first flexible thin film encapsulatinglayer, a thin-film transistor (TFT) array, an OLED device, a secondflexible thin film encapsulating layer, an adhesion layer, a thirdflexible thin film encapsulating layer, and a polarizer layered inorder. One or more barrier layers are arranged on the TFT array disposedon lateral sides of the OLED device, and the second flexible thin filmencapsulating layer covers the OLED device and the one or more barrierlayers.

Furthermore, two barrier layers are disposed at intervals on the lateralsides of the flexible OLED device.

Furthermore, the cross section of the barrier layer is trapezoidal inshape.

Furthermore, the barrier layer is fabricated from a negativephotoresist.

Furthermore, the TFT array is set as a reference point, and height ofthe barrier layer is larger than height of the OLED device.

Furthermore, the TFT array is set as a reference point, and height ofthe barrier layer is larger than height of the OLED device.

Furthermore, the flexible substrate is fabricated from either polyimide(PI) or polyethylene terephthalate (PET).

Furthermore, the first flexible thin film encapsulating layer, thesecond flexible thin film encapsulating layer, and the third flexiblethin film encapsulating layer all comprise an inorganic barrier layerand an organic buffer layer layered alternatively.

Furthermore, the inorganic barrier layer comprises a plurality of layersfabricated by one or more materials selecting from Al₂O₃, SiN_(x), orSiCN, and the organic buffer layer comprises a plurality of layersfabricated by one or more materials selecting from pp-HMDSO, Arcyl, orAlucone.

Furthermore, the OLED device comprises an anode formed on the TFT array,an organic function layer formed on the anode, and a cathode formed onthe organic function layer.

According to the present invention, a flexible display device comprisesan encapsulating structure for encapsulating a flexible organiclight-emitting diode (OLED) device as mentioned above and a drivingmodule.

Compared with the prior art, The encapsulating structure forencapsulating the flexible organic light-emitting diode (OLED) deviceproposed by the present invention is that, the first step of arrangingone or more barrier layer on the lateral sides of the OLED device, andthe second step of covering a flexible thin film encapsulating layer onthe one or more barrier layer. Water vapor and oxygen can be blocked offmuch better by the lateral sides of the OLED device using the presentflexible OLED device so that the lifespan of the OLED device can beprolonged.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a conventional encapsulating structure of the flexible OLEDdevice.

FIG. 2 shows an encapsulating structure of the flexible OLED deviceaccording to a preferred embodiment of the present invention.

FIG. 3 shows a top view of the barrier layer according to a preferredembodiment of the present invention.

FIG. 4 illustrates a schematic diagram of the OLED device according to apreferred embodiment of the present invention.

FIG. 5 shows a flexible thin film encapsulating structure layeraccording to a preferred embodiment of the present invention.

FIG. 6 shows a block diagram of the flexible display device according toa preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

For better understanding embodiments of the present invention, thefollowing detailed description taken in conjunction with theaccompanying drawings is provided. Apparently, the accompanying drawingsare merely for some of the embodiments of the present invention. Anyordinarily skilled person in the technical field of the presentinvention could still obtain other accompanying drawings without uselaborious invention based on the present accompanying drawings.

The accompanying drawings illustrate embodiments of the invention and,together with the description, serve to explain the principles of theinvention. The irrelevant structure or/and steps are omitted.

An encapsulating structure 100 comprising a flexible OLED device isproposed by the present embodiment. As FIG. 2 shows, the encapsulatingstructure 100 comprises a flexible substrate 10, a first flexible thinfilm encapsulating layer 20, a TFT array 30, an OLED device 40, a secondflexible thin film encapsulating layer 50, an adhesion layer 60, a thirdflexible thin film encapsulating layer 70, and a polarizer 80 layered inorder. Please refer to FIG. 2 and FIG. 3. Two barrier layers 90 aredisposed at intervals on the lateral sides of the OLED device 40 of theTFT array 30. The second flexible thin film encapsulating layer 50covers the OLED device 40 and the barrier layers 90. It is notified thatit is possible that only one barrier layer 90 is used in one embodiment.It is also possible that a plurality of barrier layers 90 are adopted inone embodiment.

Because the barrier layer 90 is arranged on the lateral sides of theOLED device 40 in the encapsulating structure 100, exterior water vaporand oxygen is blocked off by both of the barrier layer 90 and the secondflexible thin film encapsulating layer 50. Since the sides of the OLEDdevice 40 blocks off water vapor and oxygen better, the lifespan of theOLED device is prolonged.

The barrier layer 90 can be fabricated from a negative photoresist.

As FIG. 2 shows, the cross section of the barrier layer 90 istrapezoidal in shape. The structure of the barrier layer 90 can be atrapezoidal abutment with a larger slope so that the second flexiblethin film encapsulating layer 50 can cover the barrier layer 90 better.Also, the second flexible thin film encapsulating layer 50 and thebarrier layer 90 can match better.

Please refer to FIG. 2. The TFT array 30 is set as a reference point.The height of the barrier layer 90 is larger than the height of the OLEDdevice 40 for achieving a better effect of blocking off water vapor andoxygen. It is notified that, in general, the TFT array 30 comprises aTFT display section and an encapsulating section located on theperiphery of the display section (not shown). The OLED device 40 isarranged on the display section. The barrier layer 90 is arranged on theencapsulating section.

Please refer to FIG. 4. The OLED device 40 comprises an anode 41 formedon the TFT array 30, an organic function layer 42 formed on the anode41, and a cathode 43 formed on the organic function layer 42. The anode41 and the cathode 43 excite the organic function layer 42 forsuccessful display. The organic function layer 42 is formed by threefunction layers (not shown). The three function layers are a holetransport layer (HTL), an emissive layer (EML), and an electrontransport layer (ETL). Each of the three function layers may be a singlelayer or more than one layer. For example, the HTL may further comprisea hole injection layer and a hole transportation layer, or the ETL mayfurther comprise an electron transportation layer and an electroninjection layer. The functions of the hole injection layer and thefunctions of the hole transportation layer are similar so they are takenas the HTL. The functions of theses layers are similar so they areregarded as the HTL and the ETL in general.

The flexible substrate 10 can be fabricated from either polyimide (PI)or polyethylene terephthalate (PET).

The first flexible thin film encapsulating layer 20, the second flexiblethin film encapsulating layer 50, and the third flexible thin filmencapsulating layer 70 all comprise an inorganic barrier layer and anorganic buffer layer layered alternatively. Take the first flexible thinfilm encapsulating layer 20 for example. Please refer to FIG. 5. Thefirst flexible thin film encapsulating layer 20 comprises a firstorganic buffer layer 21, a first inorganic barrier layer 22, a secondorganic buffer layer 21, and a second inorganic barrier layer 22 layeredalternatively. Both of the second flexible thin film encapsulating layer50 and the third flexible thin film encapsulating layer 70 also have thestructure as mentioned above. When it comes to the number of the organicbuffer layer 21 and the number of the inorganic barrier layer 22 usedfor alternative arrangement, practical demands are taken intoconsiderations. In general, it is positively related between thecapacity of the flexible thin film encapsulating layers to block offwater vapor and oxygen and the number of layers of the flexible thinfilm encapsulating layers. The inorganic barrier layer can be fabricatedfrom material such as Al₂O₃, SiN_(x), or SiCN. Also, the inorganicbarrier layer can comprise a plurality of arbitrary layers fabricatedfrom two or more than two kinds of materials. The organic buffer layercan be fabricated from material such as pp-HMDSO, Arcyl, or Alucone.Also, the inorganic barrier layer can comprise a plurality of arbitrarylayers fabricated from two or more than two kinds of materials.

Further, a flexible display device is proposed by the presentembodiment. As FIG. 6 shows, the flexible display device comprises theencapsulating structure 100 comprising the flexible OLED device and adriving module 200. The driving module 200 is used for supplying theencapsulating structure 100 comprising the flexible OLED device with adriving signal so that the flexible OLED device can illuminate.

To sum up, the encapsulating structure comprising the flexible OLEDdevice proposed by the present invention is that, the first step ofarranging one or more barrier layer on the lateral sides of the OLEDdevice, and the second step of covering a flexible thin filmencapsulating layer on the one or more barrier layer. Water vapor andoxygen can be blocked off much better by the lateral sides of the OLEDdevice so that the lifespan of the OLED device can be prolonged.

The terms “a” or “an”, as used herein, are defined as one or more thanone. The term “another”, as used herein, is defined as at least a secondor more. The terms “including” and/or “having” as used herein, aredefined as comprising. It should be noted that if it is described in thespecification that one component is “connected,” “coupled” or “joined”to another component, a third component may be “connected,” “coupled,”and “joined” between the first and second components, although the firstcomponent may be directly connected, coupled or joined to the secondcomponent.

While the present invention has been described in connection with whatis considered the most practical and preferred embodiments, it isunderstood that this invention is not limited to the disclosedembodiments but is intended to cover various arrangements made withoutdeparting from the scope of the broadest interpretation of the appendedclaims.

What is claimed is:
 1. An encapsulating structure for encapsulating aflexible organic light-emitting diode (OLED) device, comprising: aflexible substrate, a first flexible thin film encapsulating layer, athin-film transistor (TFT) array, an OLED device, a second flexible thinfilm encapsulating layer, an adhesion layer, a third flexible thin filmencapsulating layer, and a polarizer layered in order wherein one ormore barrier layers are arranged on the TFT array disposed on lateralsides of the OLED device, and the second flexible thin filmencapsulating layer covers the OLED device and the one or more barrierlayers, wherein the OLED device comprises an anode formed on the TFTarray, an organic function layer formed on the anode, and a cathodeformed on the organic function layer.
 2. The encapsulating structure forencapsulating the flexible organic light-emitting diode (OLED) device ofclaim 1, wherein two barrier layers are disposed at intervals on thelateral sides of the flexible OLED device.
 3. The encapsulatingstructure for encapsulating the flexible organic light-emitting diode(OLED) device of claim 1, wherein the cross section of the barrier layeris trapezoidal in shape.
 4. The encapsulating structure forencapsulating the flexible organic light-emitting diode (OLED) device ofclaim 1, wherein the barrier layer is fabricated from a negativephotoresist.
 5. The encapsulating structure for encapsulating theflexible organic light-emitting diode (OLED) device of claim 1, whereinthe TFT array is set as a reference point, and height of the barrierlayer is larger than height of the OLED device.
 6. The encapsulatingstructure for encapsulating the flexible organic light-emitting diode(OLED) device of claim 3, wherein the TFT array is set as a referencepoint, and height of the barrier layer is larger than height of the OLEDdevice.
 7. The encapsulating structure for encapsulating the flexibleorganic light-emitting diode (OLED) device of claim 1, wherein theflexible substrate is fabricated from either polyimide (PI) orpolyethylene terephthalate (PET).
 8. The encapsulating structure forencapsulating the flexible organic light-emitting diode (OLED) device ofclaim 1, wherein the first flexible thin film encapsulating layer, thesecond flexible thin film encapsulating layer, and the third flexiblethin film encapsulating layer all comprise an inorganic barrier layerand an organic buffer layer layered alternatively.
 9. The encapsulatingstructure for encapsulating the flexible organic light-emitting diode(OLED) device of claim 8, wherein the inorganic barrier layer comprisesa plurality of layers fabricated by one or more materials selecting fromAl₂O₃, SiN_(x), or SiCN, and the organic buffer layer comprises aplurality of layers fabricated by one or more materials selecting frompp-HMDSO, Arcyl, or Alucone.
 10. A flexible display device comprising anencapsulating structure for encapsulating a flexible organiclight-emitting diode (OLED) device and a driving module, theencapsulating structure comprising: a flexible substrate, a firstflexible thin film encapsulating layer, a thin-film transistor (TFT)array, an OLED device, a second flexible thin film encapsulating layer,an adhesion layer, a third flexible thin film encapsulating layer, and apolarizer layered in order wherein one or more barrier layers arearranged on the TFT array disposed on lateral sides of the OLED device,and the second flexible thin film encapsulating layer covers the OLEDdevice and the one or more barrier layers, wherein the OLED devicecomprises an anode formed on the TFT array, an organic function layerformed on the anode, and a cathode formed on the organic function layer.11. The flexible display device of claim 10, wherein two barrier layersare disposed at intervals on the lateral sides of the flexible OLEDdevice.
 12. The flexible display device of claim 10, wherein the crosssection of the barrier layer is trapezoidal in shape.
 13. The flexibledisplay device of claim 10, wherein the barrier layer is fabricated froma negative photoresist.
 14. The flexible display device of claim 10,wherein the TFT array is set as a reference point, and height of thebarrier layer is larger than height of the OLED device.
 15. The flexibledisplay device of claim 12, wherein the TFT array is set as a referencepoint, and height of the barrier layer is larger than height of the OLEDdevice.
 16. The flexible display device of claim 10, wherein theflexible substrate is fabricated from either polyimide (PI) orpolyethylene terephthalate (PET).
 17. The flexible display device ofclaim 10, wherein the first flexible thin film encapsulating layer, thesecond flexible thin film encapsulating layer, and the third flexiblethin film encapsulating layer all comprise an inorganic barrier layerand an organic buffer layer layered alternatively.
 18. The flexibledisplay device of claim 17, wherein the inorganic barrier layercomprises a plurality of layers fabricated by one or more materialsselecting from Al₂O₃, SiN_(x), or SiCN, and the organic buffer layercomprises a plurality of layers fabricated by one or more materialsselecting from pp-HMDSO, Arcyl, or Alucone.